Nowadays, physiological amino acids profiling is based primarily on ion exchange chromatography (IEC) coupled to a post-column derivatization with ninhydrin and UV detection at two wavelengths ... [more ▼]

Nowadays, physiological amino acids profiling is based primarily on ion exchange chromatography (IEC) coupled to a post-column derivatization with ninhydrin and UV detection at two wavelengths. Unfortunately, this technique suffers various drawbacks such as long analysis time, high sample volume and specific costs related to the maintenance of a dedicated equipment. These reasons have led us to consider a technology switch to a mass spectrometry method. We tested the kit aTRAQ amino acids analysis for physiological samples (AB Sciex), offering a selective quantification of more than 40 amino acids, and have implemented the acquisition of various original markers to the initial method. The accuracy profiles established for each amino acid show that the results are very reliable. The linearity is assured between 1 and 1.000 mumol/L for most analytes. Result comparison with IEC method showed good agreement. Reference ranges are similar to those defined for the IEC method and patients with inborn errors of metabolism were readily identified. The aTRAQ method offers a valid alternative to IEC method with several advantages: reduced sample volume, decreased run time and increased specificity. However, the procedure requires a thorough review of all chromatographic peaks, process that considerably lengthens the overall time of the procedure. Finally, financial and practical considerations of both techniques have to be counterbalanced before initiating any methodological transition. [less ▲]

in Journal of chromatography. B, Analytical technologies in the biomedical and life sciences (2015), 997

BACKGROUND: Hypoglycin A has been recently identified has the causal agent of atypical myopathy (AM) in horses. Its identification and quantification in equine's biological fluids is thus a major concern ... [more ▼]

BACKGROUND: Hypoglycin A has been recently identified has the causal agent of atypical myopathy (AM) in horses. Its identification and quantification in equine's biological fluids is thus a major concern to confirm maple poisoning and to provide insight into the poorly understood mechanism of hypoglycin A intoxication. METHODS: Quantification of hypoglycin A has been achieved with the aTRAQ kit for amino acid analysis of physiological fluids (AB Sciex). Acquisition method on mass spectrometer has been updated to record the hypoglycin A specific MRM transition. RESULTS: Outlined accuracy profiles demonstrated very reliable data. A good linearity was observed from 0.09 to 50mumol/L and precision was very good with coefficient of variation below 8%. Fifty-five samples collected from 25 confirmed AM horses revealed significant hypoglycin A concentrations, while toxin was not found in serum of 8 control animals. CONCLUSIONS: The described aTRAQ variant method has been analytically and clinically validated. The reliability of our approach is thus demonstrated into the workup of atypical myopathy. [less ▲]

Carnitine palmitoyltransferase II (CPT2) deficiency is a rare inborn error of mitochondrial fatty acid metabolism associated with various phenotypes. Whereas most patients present with postnatal signs of energetic failure affecting muscle and liver, a small subset of patients presents antenatal malformations including brain dysgenesis and neuronal migration defects. Here, we report recurrence of severe cerebral dysgenesis with Dandy-Walker malformation in three successive pregnancies and review previously reported antenatal cases. Interestingly, we also report that acylcarnitines profile, tested retrospectively on the amniotic fluid of last pregnancy, was not sensitive enough to allow reliable prenatal diagnosis of CPT2 deficiency. Finally, because fetuses affected by severe cerebral malformations are frequently aborted, CPT2 deficiency may be underestimated and fatty acid oxidation disorders should be considered when faced with a fetus with Dandy-Walker anomaly or another brain dysgenesis. [less ▲]

During an 18-month period, we noticed an alarming increase of newborn screening false positivity rate in identifying isovaleric acidemia. In 50 of 50 newborns presenting elevated C5-carnitine, we confirmed the presence of pivaloylcarnitine. Exogenous pivalate administration had been previously identified as the causal agent of this concern. No pivalic-ester prodrug is commercially available in Belgium, but pivalic derivates are also used in the cosmetic industry as emollient under the term "neopentanoate". We have identified neopentanoate-esters in a nipple-fissure unguent that was provided to young mothers. Ceasing distribution of this product hugely reduced the C5-carnitine false positivity rate. [less ▲]

Purpose: To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries. Methods: A database of 767,464 ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are common in North America and in some European countries. Isoelectric Focusing or High Performance Liquid Chromatography is the main technique used for hemoglobin variant detection. METHODS: Since tandem mass spectrometry is being used for screening of inherited metabolic disorders and allows protein identification, we had developed an application to identify the most relevant hemoglobin mutations with this technology. RESULTS: This approach had been previously validated and has been routinely applied in our laboratory for the last three years. We report here our experience with this new method in the field, applied to our East-Belgian population. CONCLUSIONS: To conclude, mass spectrometry provides an efficient alternative approach for laboratories performing neonatal screening of hemoglobin disorders. [less ▲]

To prevent the severe developmental and physical morbidities associated with congenital hypothyroidism, we developed a home-made Enzyme-Linked Immunosorbent Assay (ELISA) method to quantify Thyroid Stimulating Hormone (TSH) levels on newborn dried blood spots. In order to agree with actual clinical laboratory quality referential (ISO 15189), we desired to update our analytical validation protocol. For this purpose, an approach using accuracy profiles based on tolerance intervals for the total error measurement was for first time applied to an immunological assay. According to acceptance limits fixed at +/-30%, the method was found accurate over a concentration range from 17.48 to 250mIU/L. Based on 99.5 percentile of a 16,459 newborn population, cut-off was fixed at 20.1mIU/L and validated against normal and pathologic neonatal populations. Additionally, uncertainty regions around this value were obtained applying four different approaches. Finally, we demonstrated here our in-house immunological technique fulfils criterions of a neonatal screening policy. [less ▲]

BACKGROUND: Neonatal screening programs for sickle cell disease are now widespread in North American and European countries. Most programs apply isoelectric focusing or HPLC to detect hemoglobin variants ... [more ▼]

BACKGROUND: Neonatal screening programs for sickle cell disease are now widespread in North American and European countries. Most programs apply isoelectric focusing or HPLC to detect hemoglobin variants. Because tandem mass spectrometry (MS/MS) is being used for screening of inherited metabolic disorders and allows protein identification, it was worth testing for hemoglobinopathy screening. METHODS: We minimized sample preparation and analysis times by avoiding prior purification, derivatization, or separation. We developed a tryptic digestion methodology to screen for the main clinically important variants (HbS, HbC, and HbE) and beta-thalassemia. To ensure proper discrimination between homozygote and heterozygote variants, we selected 4 transitions with good signal intensities for each specific peptide and calculated variant/HbA ratios for each. Method validation included intra- and interseries variability, carryover, and limit of detection. We also performed a comparative study with isoelectric focusing results on 2082 specimens. RESULTS: Intraassay imprecision values (CVs) varied between 2.5% and 30.7%. Interassay CVs were between 6.3% and 23.6%. Carryover was <0.03%, and the limit of detection was fixed at 1% of HbS. According to the MS/MS settings (detection of HbS, HbC, HbE, and beta-globin production defects), the comparative study did not yield any discrepant results between the 2 techniques. CONCLUSIONS: MS/MS is a reliable method for hemoglobinopathy neonatal screening. [less ▲]

Hunter syndrome (or Mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder due to the deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in the accumulation of heparan and ... [more ▼]

Hunter syndrome (or Mucopolysaccharidosis type II, MPS II) is an X-linked recessive disorder due to the deficiency of the iduronate-2-sulfatase (IDS) enzyme, resulting in the accumulation of heparan and dermatan sulfates in the lysosomes. The heterogeneity of clinical phenotypes, ranging from mild-to-severe forms, is a result of different mutations in the IDS gene. We report here, a novel nonsense mutation (p.Y54X) in two siblings MPS II African patients affected with a severe form of the disease. We postulated that the p.Y54X mutation which causes a loss of the IDS region highly conserved among sulfatase enzymes, could be predicted as a severe disease-causing mutation for Hunter syndrome. [less ▲]

Objectives To evaluate the feasibility of systematic neonatal screening for sickle cell disease in the region of Great Lakes in Central Africa using a new approach with limited costs. Methods Between July ... [more ▼]

Objectives To evaluate the feasibility of systematic neonatal screening for sickle cell disease in the region of Great Lakes in Central Africa using a new approach with limited costs. Methods Between July 2004 and July 2006, 1825 newborn dried blood samples were collected onto filter papers in four maternity units from Burundi, Rwanda and the East of the Democratic Republic of Congo. We tested for the presence of haemoglobin C and S in the eluted blood by an enzyme-linked immunosorbent assay (ELISA) test using a monoclonal antibody. All ELISA-positive samples (multiple of the median (MoM) >= 1.5) were confirmed by a simple molecular test. The statistica software version 7.1 was used to create graphics and to fix the MoM cut-off, and the chi(2) of Pearson was used to compare the genotype incidences between countries. Results Of the 1825 samples screened, 97 (5.32%) were positive. Of these, 60 (3.28%) samples were heterozygous for Hb S, and four (0.22%) for Hb C; two (0.11%) newborns were Hb SS homozygotes. Conclusions The lower cost and the high specificity of ELISA test are appropriate for developing countries, and such systematic screening for sickle cell anaemia is therefore feasible. [less ▲]

Setting Early diagnosis of sickle cell disease decreases morbidity. However, cost-effective screening programmes are not yet available. Methods We explored the feasibility of systematic screening performed on dried blood harvested from five-day-old newborns. Results A total of 27,010 samples were collected in Belgian maternity units between June 2003 and February 2005, and the presence of haemoglobin (Hb) C or S in the eluted blood was examined by an enzyme-linked immunosorbent assay (ELISA) test performed with a monoclonal antibody detecting both mutated forms. As this antibody slightly cross-reacts with Hb A, better specificity is achieved if the test is performed not later than day 5. Among the 27,010 samples, 132 (0.49%) were positive. Molecular biology tests performed on dried blood from positive samples showed that 106 of these babies were heterozygotes for the Hb S mutation and three were heterozygotes for the Hb C mutation, while three newborns were SS homozygotes (0.011%). Seventeen samples (0.063%) were false-positives as we could not detect any mutation. Conclusions We have developed a new immunological approach in the field of haemoglobinopathy neonatal screening. This ELISA test is cheap (E0.2 /test or E1800/cletected SS homozygote) and could be centralized. Its cost-effectiveness in the whole Belgian population is comparable with that of screening for phenylketonuria or congenital adrenal hyperplasia. Further improvements should obviously be achieved in order to better discriminate heterozygotes and homozygotes, but the accessibility and the low cost of the test are relevant arguments for the screening extension in a wide range of countries, especially in Central Africa. [less ▲]

In South Belgium (Wallonia), the 'triple test' was introduced in 1990-1991, and is nowadays a widely accepted screening method for assessment of trisomy 21 risk in pregnancy. The 'triple test' is not ... [more ▼]

In South Belgium (Wallonia), the 'triple test' was introduced in 1990-1991, and is nowadays a widely accepted screening method for assessment of trisomy 21 risk in pregnancy. The 'triple test' is not regulated and can be freely performed by any biomedical lab, making epidemiological data unavailable. By contrast, cytogenetic investigations are limited to a few genetic centres, and accurate statistics can be easily built from their files. During the period 1984-1989, a total of 244 trisomy 21 (1/876 pregnancies) were diagnosed in the Genetic Centres of Liege and Loverval, 42 (17%) of them prenatally. During the period 1993-1998, 294 trisomy 21 (1/704 pregnancies) were observed, 165 (56%) of which prenatally, and more than 90% of affected pregnancies were terminated. Even after correction for late foetal loss of trisomic foetuses, the difference is highly significant, and corresponds to a theoretical shift in the incidence of trisomy 21 at birth from 1/794 to 1/1606. As no remarkable progress occurred in other non-invasive prenatal screening procedures or general health care policies in Belgium, the most reasonable explanation is the use on a large scale of triple test by pregnant women, and the election of termination for most affected pregnancies. [less ▲]

in American Journal of Obstetrics and Gynecology (1995), 172(1, Pt 1), 167-74

OBJECTIVE: The feasibility of large-scale Down syndrome maternal screening with dried blood samples and nonradioactive methods was examined. STUDY DESIGN: A prospective observation study was performed on ... [more ▼]

OBJECTIVE: The feasibility of large-scale Down syndrome maternal screening with dried blood samples and nonradioactive methods was examined. STUDY DESIGN: A prospective observation study was performed on a nonselected population of 11,241 pregnant women sampled between January 1991 and September 1992, between 14 and 24 weeks' gestation (ultrasonographic scanning available for 91.6%), through a multicenter collaborative network. Enzyme-linked immunosorbent assays for alpha-fetoprotein, human chorionic gonadotropin, and free estriol were performed on dried blood samples. Risk determination was made with an in-house software implementing the multivariate gaussian log likelihood method. RESULTS: A total of 10,450 samples were eligible for the study. Mean age at term was 27.9 years. A total of 6.84% of the patients were > or = 35 years old with a prior risk of trisomy 21 > 1:350. The general positive rate of our sample was 8.15%. After calculation 31.7% with prior risk > 1:350 were still in the high-risk group; 6.36% of the low-risk group were found to be at high risk for Down syndrome. Fifteen trisomic pregnancies were observed, of which 11 had a calculated risk higher than the selected cutoff value (1:350). The overall detection rate was 73%, specificity was 92%, and positive predictive power was 1.2%. CONCLUSION: Our pilot study has shown performances within the range of conventional serum screening programs. Dried blood assays are a handy alternative to serum assays. Blot paper cards represent a simple method of sampling, well fitted for large population screening. Combined with nonradioactive methods, this method appears to be both low cost and effective. The current work apparently is the first large-scale Down screening program performed with dried blood. [less ▲]